1. Field of the Invention
Embodiments of the present invention relate to a wet etching solution. More specifically, embodiments of the present invention relate to a wet etching solution having an improved oxide selectivity.
2. Description of the Related Art
In general, semiconductor devices and display devices, e.g., liquid crystal displays (LCDs), organic light-emitting diode (OLED) displays, plasma display panels (PDPs), and so forth, may be fabricated by, e.g., photolithography. Photolithography may include several processes, e.g., etching.
Etching refers to a process of removing predetermined portions of material by wet etching, i.e., removal of material via application of a chemical, or by dry etching, i.e., removal of material via plasma. As opposed to dry etching, wet etching may be isotropic, i.e., removal of material in all directions at the same rate, thereby being suitable for use in three-dimensional devices, e.g., metal wiring or contact holes in a semiconductor device. For example, portions of an oxide layer may be etched to form and/or to expose active regions, e.g., source/drain regions, gate regions, and so forth, on a semiconductor substrate.
Conventional wet etching may include a buffered oxide etchant (BOE), e.g., a diluted hydrofluoric acid (HF) solution containing ammonium fluoride. However, conventional wet etchants may have low oxide selectivity, i.e., a ratio between etching rates of different materials, thereby causing incorrect etching of the oxide materials and of structures adjacent thereto, e.g., a metal silicide (MSix) gate stack. In other words, application of a conventional wet etching solution to an oxide material may cause excessive etching of elements adjacent thereto, thereby damaging the adjacent elements. For example, the conventional BOE may have a very high etching ratio of metal silicide to silicon oxide, e.g., remove portions of metal wiring about five to ten times faster than portions of the oxide material.